When it comes to the most discriminating nose in the animal kingdom, the elephant may be the winner by a long shot -- or a long trunk along with the most olfactory receptor genes of any creature on earth, a study found.
Elephants have around 10,000 genes devoted to smell, the most ever detected in any animal, twice that of domestic dogs and a full five times the number possessed by humans.
However, the scientists behind the study acknowledge there may not be a direct connection linking the possession of the most genes with being the best "sniff artist" on Earth.
"We don't really know how the number of olfactory receptor genes relates to olfactory ability," says lead study author Yoshihito Niimura of the University of Tokyo's department of applied biological chemistry.
"For example, dogs are known for their keen sense of smell -- but we actually already knew that their number of genes was much smaller than mice, who we don't see with that same ability."
Dogs' noses are undeniably sensitive, he says, but perhaps not all that discerning between different smells, even if they can smell a human from just a very low concentration of odor molecules.
Under that criteria their sense of smell is probably more sensitive than an elephant's, but where the pachyderms come out ahead is likely in their ability to identify a broader range of smells, Niimura says.
Previous studies of Asian elephants have shown they possess the ability to differentiate between odor molecules that are extremely similar, a skill humans and primates have never developed.
For example, the researchers said, elephants are able to recognize another individual elephant by the minuscule differences in odor molecules in their urine.
It's that long trunk of elephants that's likely why they've come to rely so heavily on their sense of smell, since the trunk has many uses in addition to being the animal's sniffer, primarily as their main way of interacting with their world, Niimura says.
"Imagine having a nose on the palm of your hand," he says. "Every time you touch something, you smell it!"
The old cliché "an elephant never forgets" may have some basis in truth, and that basis may reside in their noses, Niimura speculates, which helps them distinguish -- and thus possibly remember -- a great number of people and places from one another.
"But I must make a point of saying," Niimura adds, "that elephants are very intelligent."
By which he means, he says, a good nose isn't much use unless it goes with a good brain able to turn smells into knowledge.
Still, it can't hurt that elephants can smell a human from more than a half-mile away.
